Field of the Disclosure
The present disclosure relates to an array substrate for an X-ray detector and an X-ray detector comprising the same, and more particularly, to an array substrate for an X-ray detector and an X-ray detector including the same, for capable of separately measuring characteristics of a transistor and an optical detector of the X-ray detector with a high accuracy.
Description of the Background
An X-ray inspection method that has been widely used for medical diagnosis requires an X-ray sensing film and a film printing time to obtain a result.
However, recently, by virtue of development of semiconductor technologies, a digital X-ray detector using a thin film transistor (TFT) has been researched and developed. The digital X-ray detector advantageously diagnoses a result in real time immediately after an X-ray is taken by using a TFT as a switching device.
In general, two different types are used in the digital X-ray detector; a direct type DXD method and an indirect type DXD method. The direct type DXD method is detecting current by as much as electric charges received from a selenium layer by a pixel electrode of a TFT and performing a signaling processing procedure using a structure including an amorphous Se layer stacked on a TFT array substrate and a transparent electrode formed on the amorphous Se layer. The indirect type DXD method is converting a visible ray into an electrical signal by a PIN diode and performing a series of signal processing procedures when an X-ray is converted into the visible ray by a scintillator.
Recently, an X-ray detector using an indirect type DXD method has been most spotlighted. The X-ray detector includes an optical diode formed on an array substrate to detect an X-ray, and a scintillator disposed on the optical diode.
FIG. 1 is a schematic diagram illustrating a cesium-applied area 2 of a scintillator in an X-ray detector. FIG. 2 is a schematic diagram of a test pattern present outside an array substrate in the conventional X-ray detector. As illustrated in FIG. 1, the cesium-applied area 2 of the scintillator is formed over an active area of an array substrate 1 such that it does not overlap connection lines 3 for connecting COFs with signal lines of the array substrate. In this regard, there is a problem in that a cesium component corrodes metallic lines of the array substrate 1 of a thin film transistor, and thus an uppermost layer of the active area of the array substrate is typically protected by an organic layer. Accordingly, as illustrated in FIG. 2, a test pattern is added to an edge portion of a sheet material of a base substrate outside the array substrate to thereby evaluate panel characteristics. However, the test pattern added to the edge portion of the sheet material of the base substrate is distant from the active area of the array substrate, and thus the accuracy of the test is lowered.
In addition, in the X-ray detector, a thin film transistor and an optical diode are present in one pixel due to the structural characteristics, and thus the characteristics of both the thin film transistor and the optical diode are shown together. Accordingly, it is difficult to evaluate unique characteristics of each of the thin film transistor and optical diode. Therefore, a solution for the issue is necessary.